keinath



April 1945. KElNATH Re; 22,637

MEASURING SYSTEM Original Filed March 21;, 1941 2 Sheets-Sheet l GEO/P65 Kev/VA 7/14 A TTORNEYS.

1N VE NTOR.

April 24, v1945. I Q mA H Re. 22,637

I I MEASURING $YSTEM I rlginal File d March "21, 1941 "2 Sheets-Sheet 2 v I INVENTOR.

- 9 GEO/P65 KE/A/A 7M LO BY .A T'TORNEYS.

ing circuit arrangement.

aeinuea Apr. 24, 1945 UNITED George Keinath, Larchmont, N. 1'. Original No. 2,321,605, dated June is, 194:, Serial No. 384,489, March 21, 1941. Application torreissue April 22, 1944, Serial No. 532,817

. easily permit operations involving wattmetric 18 Claims.

My invention relates to electric measuring systems in which a mechanism for indicating, recording, signalling or control purposes is actuated in accordance with a variable control magnitude and by means of an automatically operat- It is known to provide such systems with a baianceable network as represented by a. Wheat stone bridge. a potentiometer circuit or the like. These networks have a zero'instrument or zero relay, variable circuit means for supplying the primary control magnitude, and an adjustable impedance member for compensating .the effect of the variable circuit means on the zero relay. A departure of the control magnitude from a datum value causes the balance of the network to be disturbed so that the zero relay deflects from it position of rest. As a result, the relay energizes the circuit 01' drive means which in turn control the adjustable impedance member of the measuring network so as to reestablish the balance condition. when the network is balanced, a condition which the system tends to maintain automatically, the adiustment of the impedance member and of any indicating, recording or control device coupled therewith,- corresponds to the primary control magnitude. Self-balancing measuring systems of this known ty are applicable for various measuring and control purposes, for instance for indicating and recording variable pressure, temperature, voltage and current magnitudes, for automatically controlling furnaces and other devices, in summary for determining, signalling, indicating, recording, or using for control purposes any variable magnitude of electrical nature or convertible into a variation of such nature and apt to efiect the balance of the abovementioned measuringnetwork.

- There are, however, some limitations attached to these known systems. First, the automatic control of the adjustable impedance is relatively sluggish. Customary recorders, for instance, re-

quire an adjusting period of about one or several seconds. systemwhen fast-changing magnitudes are to be recorded, Secondly, the accuracy and reliability of the kricwnsystems is limited. This is partly also due to the relatively long time necessary for the automatic follow-up adjustments. Furthermore, many of the known systems of the type.

here in point are too complicated and sensitive for many purposes and, when designed for one purpose, do not lend themselves easily for other purposes. For instance, some known systems operate for D. C. measurements only; others do not measurements.

It is an object of my invention to provide an electric systemwhich is applicable for purpose of the above-mentioned kind yet superior to the known systems by reducing or avoiding one or. several of their disadvantages.

More specifically, an object oi the invention is to increase the field of applicability and in improve the accuracy of measuring systems for such purposes as here referred to.

This renders it impossible to use the Another object, related to the foregoing, is to provide a measuring system for indicating, signalling, recording, control or the like purposes, with a self-balancing network whose automatic adjustment. so as to perform the desired operation, requires less time than in the above-described systems. For' instance, the invention aims at reducing this adjusting time to periods in the order of fractions down to one or a few tenths of one second or less.

Other objects of my invention deal with the provision and improvement of indicating means, applicable in systems of the type here of interest. An object, in this respect, is to aflord an indication not only of the instantaneous value or the primary magnitude to be determined, but also the tendency of variation or the rate of change of this magnitude.

A further object i concerned with providing an improved mechanism of relatively simple construction for control and regulating purposes, such as the control of the temperature in rooms or furnaces or the control of manufacturing operations, so as to eflect an automatic selection from two or more possible control operations dependent upon the instantaneous value of the variable primary control magnitude. A more for primary control magnitudes representing a voltage or current intensity or an electric energy, for measuring D. C. magnitudes or A. C. magnitudes in single-phase or. multiphase circuits;

According to my invention. in one oi its aspects, an electric system for indicating, signalling, recording or control purposes, is constructed as folment which includes the circuit means ior prolows. The system contains a circuit arrangeviding the variable magnitude to be determined,

. transmitted or used as pilot magnitude 01' a desired control operation. This variable magnia differential type relay being appropriate for this purpose.

The periodic adjustments of the impedance member and the movable mechanism member need not necessarily lbe of equal speed or equal rate of change so long as their relation to each other is univocal, and there are occasions where diflerentspeeds orvv diiierent paths of movement tude, for simplicity sake, is called "primary-control magnitude" in the following description as well as in several of the claims. The circuit arrangement also contains a measuring instrument of the like designed as a relay, and an adjustable justable impedance member. Consequently, any

deviation of the primary control magnitude from a datum value requires a corresponding definite variation of the adjustable impedance member in order to reestablish the previous circuit conditions as regards the relay. The system further contains drive means which vary the adjustment of the impedance member periodically over a range including those adjustments which may become necessary to compensate for any utilizable variation of the primary control magnitude. Hence, the impedance member passes repeatedly through the compensating adjustment when actuated by the drive means. Another element of the system is a mechanism to be controlled in accordance with the primary control magnitude. This mechanism has a movable member actuated periodically in a given relation to the periodic adjustment oi the impedance member so that each position assumed by the movable member circuit and causes this circuit to pass an impulse to the movable member at the moment when the relay responds to a given current condition in the network. Since at the same moment the movable member is at a point of its travel which corresponds to theprimary control magnitude, the periodic indications or controloperations effected by the energization of the movable memher are in accordance with the variations oithe primary control magnitude.

In another aspect of the invention, the circuit arrangement of a system organized as described in the foregoing, is designed as a balanceable The relay is or rates or change are advantageous; However, according to another and more specific feature 0! the invention, the two members are operated synchronously with equal or proportional rectilinear.

:orangular'sp'eed, tor instance by connecting them 1 mechanically-with each other or with a common? drive.

' Thefioregoing'and other objects and features of the'finvention" will 'become apparent from the .tollowing description of several embodiments oi the invention exemplified by the drawings in during its travel corresponds to one definite imnetwork, the measuring device or relay forming the zero instrument of the network. A network of the type of a Wheatstone bridge may be used having the relay located in the bridge diagonal or.

zero branch. According to another'modiflcation,

the circuit ar-rangementcontains two substantially separate circuits, one supplying the primary control magnitude to a relay and the other containing the adjustable impedance member,

. not in a single circuit branch but in the relay,

which,

Fig. 1 shows diagrammatically an indicating nal transmission, recording or control in depend.-

ence upon a wattmetric magnitude;

Fig. 6 illustrates the circuit diagram of another system operating with direct current and serving to control an apparatus, for instance an electric furnace, in dependence upon temperature variations; and v Fig. '1 shows a system of more elaborate design for indicating or recording temperature variations, in particular, of the blood temperature.

'In order to indicate the relationship between,

the different embodiments and to facilitate describing their details, the following general markings are used in the figures:

The indicating, recording or control mechanism to be governed by a primary control magnitude is marked inFigs. 1, 4, 6 and 7 with the letter A.

The letter B in, Figs. 1, 4 and '7 indicates measuring networks containing the circuit element for supplying the primary control magnitude, the ad justable impedance and a zero instrument, these networks B being of the bridge type and having a measuring instrument or relay connected in their bridge diagonal or zero branch.

The impulse-transmitting circuit, connecting the relay of the circuit arrangement with the movable member oi the mechanism to be controlled, is denoted by C. For simplicity sake, similar control circuits C are shown in Figs, 1 and 4 through 7, having their respective circuit elements indicated by'the same reference numerals.

The circuit arrangement of the system shown in Fig. 5 does not form a Wheatstone bridge butv contains a dynamometric relay circuit D and a compensating or potentiometer circuit Ein type similar to the circuit E in Fig. 6.

Reverting to Fig. 1 of the drawings, the meas- I uring network B contains a direct current source I00, a variable circuit'means Illi represented as a variable resistor'for furnishing the primary control magnitude. This circuit means may con--,

sist oi a resistance thermometer if the system,

to be used for measuring and indicating of the mech-' of a second, a number temperatures. For similar purposes, a thermoelement may also be employed. The bridge network B in Fig. 1 also contains an impedance III, for instance a. resistor oi constant resistance value, and, further, a rheostat I03 havin a retar! slide contact I connected with the zero or branch I00 of the bridge network. A moving coil instrument I05. .having its moving coil I00 series connected in the zero-branch I00, serves as a zero instrument and has its movable pointer provided with an intermediate contact lfl'eooperating with stationary contacts I00 and III for controlling the impulse-transmitting circult C. The indicating mechanism A contains a rotary indicator member III which is coupled with the slide contact III by means of a driving shaft III. This shaft is actuated'by motoric means (not shown) so as to rotate contact I and indicator member III in synchronism with each other and preferably with constant angular speed. The indicator II'I carries an electric illuminating means for producing light flashes, for instance a glow discharge bulb H2, which forms the pointer of the indicator and moves over a circular scale H3 indicating the magnitudes to be measured. The bulb II2 is'connected with the impulse-transmitting circuit. This circuit contains a current source III, a resistor H5 and a condenser IIB so connected with the bulb II2 and the relay contacts I01, I00 and I00 that the condenser H0 is charged by the current source 'I I0 when the bridge network is unbalanced and the intermediate contact I01 in engagement with contact I08. At the moment when the slide contact I04 passes'through the pointof its periodic travel where the 'zero branch I00 is balanced, the relay I0! is deenergized so that the contact I01 interrupts the the contact I01 thereby discharging the condenser IIB through the light bulb. The interrupti'on of the battery circuit occurs without sparking because the condenser is charged and has stopped the current flow before the contacts I01 and I00 are opened. The indicator member III, at the time when the light flash occurs, has an instantaneous position relative to the. scale Ill which corresponds to the primary control magnitude to be determined. If the driving shaft I I0 is operated with sufllcient speed, for instance so as to complete a rotation within a fraction of indicating light flashes follow one another within a short period thus conveying the appearance of a practically continuous indication of the magnitude to be determined and of any variationof this magnitude occurring during the measuring interval.

Fig. 2 exemplifies a construction of the indicating mechanism A and the adjustable rheostat. In Fig. 2, the indicator member III mounted on the driving shaft IIO serves also as a carrier for the slide contact I04 proper. gages the periphery of the annular rheostat I00 which is stationary. The glow discharge bulb H2 is mounted at the end of the indicator member III. The arrangement is enclosed by a casing II1 having a circular slot H9 covered by a transparent plate IIB. This plate is provided with the scale 3 as is apparent from the front view shown in Fig. 3. The bulb H2 is preferably provided with a diaphragm so as to give the light flash a definite and pointed shape. For instance, the shape of a trianglemay be used so that the light flash eil'ects an indication as represented in Fig. 8 by mark I20.

The above-described indicating circuit of battery Ill and engages system permits especially suitable.

This contact encated.

also an indication 0 the tendency of variation of magnitude-and also an indiof ehangeof this variation. A constructively simple method, according to the invention, for obtaining this result is to provide the transparent cover plate Ill (Fig. 2) with luminous substance. Due to the property of such substance to emit light or abating intensity after the illumination 0! the substance has ceased. an indicating mechanism thus designed shows not only an indicating (I20 in Fig. 8) but also one ormore abating light indications, such as I2I in Fig. 3. originating from preceding illuminations. The position of these other flashes oi smaller intensity indicates whether the tendency of the variations to be determinedis positive or negative. and the distance of the abating light'flasbes from the flash of greatest intensity is a measure of the rate of change of the variations. in other words, previous indication is farther away on the scale from the last indication, the primary control magnitude varies with greater speed than if the preceding and the last light flash are more closely together. a If a sumcient speed of the periodic operation is provided, more than two indications can be made to appear simultaneously on \the scale so that the tendency and rate of change of the variable magnitude are still more clearly indi- It will be obvious from the foregoing description that any other suitable measuring network may be used instead of the particular bridge arrangement shown in Fig. l. The impulse-trans- .mitting circuit C may also be designed in various ways. For instance, it suffices if the relay I05, when responding to balance conditions, connects the indicating mechanism with any current source suitablefor properly energizing the indicating mechanism.

The relay to be 'used in systems according to the invention is preferably designed as a sensitive measuring instrument and provided with a quickacting contact assembly requirin a very small deflection. Contacts with pointed pole ends are The impedance member I03, while shown as an annularrheostat with a rotating slide contact, may also be oi the linear type having an oscillating slide contact; it may consist, for instance, of a simple straight wire or a uniformly wound toroid. Rheostats formed of an un-uniformly wound toroid, or having a large number of contact laminations with resistance coils between them, are also applicable, in particular, if it is desired to obtain an indication, record or control in accordance with a desired law, for instance an indication on a logarithmic scale. The impedance member may also consist of a variable inductance, such as a variometer or a variable condenser. The variable control magnitude may also be supplied by a variable voltage source. These possibilities will be more fully understood from the embodiments described hereinafter.

According to the system illustrated in Fig. 4, the bridge network B is connected with an alternating current source 200 and contains the variable impedance 20I, for instance a resistor, capacitor or inductance coil, for supplying the primary control magnitude. 202 is an impedance of constant magnitude, and 203 the adjustable impedance member consisting of a rheostat and having a slide contact 204 connected with the zero branch 200 of the bridge. The zero instrument ofthis A. C. arrangement is-a dynamometric 1181 1; flhhh of highintensity "produced by coils 201 and 200 duces a mark at the point of member 2I I.

able circuit means 20I and, accordingly, the constant circuit means 202 are ohmic resistors, as is the case for temperature measurements, the field should be in phase with the voltage and hence with the current in the zero branch 290. However; it suflices ifthe in-phase energization is approximate, because any deviation in this respect affects only the sensitivity but not the'accuracy of measurement.

A relay of the type shown in Fig. 4 has the advantage that it permits a large number of difl'erent measuring problems in a very simple manner.

For instance, this arrangement allows measuring the loss angle of condensers. In this case, the phase position of the current in the field coils of the zero relay must be adjusted and maintained very accurately. The arrangement may also be used for measuring the capacity. of condensers. In this case, the adjustment of the phase difference between the field in the zero instrument and the voltage or current in the bridge diagonal need not be as accurate. For instance, a phase error of 5 amounts to only 0.5% capacity measurement.-

The recording mechanism proper contains a metallic transport roller 220 for actuating a paper chart 222 with constant speed. The recorder has a movable member 2 which isconnected with the movable contact 204 of the adju'stable resistor 203 by drive means indicated by broken lines and marked H0. The drive means cause the contact 204 and the movable member 2 to reciprocate simultaneously in the direction of the arrows 2I9. .The contacts I01, I08 and I09 of the zero relay are connected through the impulse-transmitting circuit C with the movable member 2I I and the roller 220 respectively.

error in the At the moment when the reciprocatory contact 204 passes through the point of its travel where the zero branch is balanced, the relay transmits a discharge impulse through the circuit C and impulse-transmitting thereby causes a flow of currentbetween the electrodes formed by the movable member 2i I and the transport roller 220. This discharge current acts electrolytically on the chemically treated paper of the recording chart, and pro- The marks produced by a series of discharges. form a curve, such as exemplified by 223, indicating the changes of the primary control magnitude to be measured.

It will be understood that the electrochemical recorder above described is mentioned merely as an example. Other recording means, in particular spark recorders, may be used instead.

When varying the adjustment of the impedance member and correspondingly actuating the movable member of the indicating, recording or control mechanism in a reciprocatory manner as exemplified by Fig. 4, the recording, indicating or the like operation of the mechanism must be blocked when the movable elements effect their return movement, because the circuit means illustrated in the foregoing examples are not demechanism in 'ment D, the relay the circuit C to transmit a control impulse mechanism when movlngin bothdirections 01' its reciprocatory travel. This can be obtained. for instance, by providing a circuit arrangement with a commutating switchwhich places the relay and impulse-transmitting circuit in proper operating condition, depending. uponthe direction of movement of the movable members. The frequency. of the periodic indications may thus be doubled. I

Some magnitudes, for instance, an electric power, cannot be easily measured .by means of a bridge network. For such cases I prefer using a circuit arrangement which also represents a zero method but contains a so-called compensating circuit. The systemsshown in Figs. 5 and 7 arev examples of such type.

Fig. 5 represents a system operating in response to variations of an electric energy. The movable member of the zero instrument 305 is again designed as a relay and serves to control the impulse-transmitting circuit C. This relay 305 is acted upon by two circuits Dand E. The circuit D includes two wattmetric energizing coils Ni and 332 of the relay 305. Current coil "I is energized by a transformer 330 in accord? ance with the current in the alternating current source 300, and the winding 332 is energized in accordance with the voltage of the current source. The circuit E contains a direct current source 34| feeding a potentiometer 344 with a constant current intensity through an automatic current-regulating device 342 and an ammeter 343. -The slide contact 345 of the potentiometer is connected with a separate control coil 340 of the relay 305, and is reciprocated as indicated by the arrow 346.

The system also contains a mechanism for indicating, recording or control purposes, having a movable member actuated in a given relation, preferably in synchronism with the slide contact 345. The mechanism is connected with the v circuit C and may be designed similar to any of the mechanisms shown in Figs, 1 through 4, 6 and 7. Hence, the operating mechanism proper is not illustrated in Fig. 5. i

The rehry 305 represents a differential apparatus-responding to the effects of both the dynamometric circuit arrangement D and the compensating circuit E. If the deflecting torque exerted by the compensating coil 340 is equal or ina predetermined relation to the deflecting torque exerted by the dynamometric arrange- 305 is balanced and causes through'the mechanism to be actuated. Consequently, the circuit arrangement of this system, viewed as a whole, also represents a balanceable arrangement operating according to a zero method, although the balance is not eifected in any single circuit but occurs within the dif-' ferential relay.

A circuit arrangement of the type exemplified by Fig. 5 is, of course, not limited to the measurement of energy magnitudes but is also applicable for any other control or measuring magnitude, such as pressure or flow conditions, voltages or current intensities. An example of the latter type, which also embodies some other modifications of the invention, is shown in Fig. 6. More particularly, Fig. 6 also exemplifies a system accordingto my invention which is applicable and especially advantageous for control purposes, for instance the automatic temperature control of a furnace.

It has been attempted for years to provide high sensitive contact instruments for control purposes. However, the control systems so far availperiod required by this known apparatus is not less than five seconds, Another type of control apparatus now on the market operates according to a deflection method and requires a high-frequency generator for eflecting a capacitive trans- 4 mission of the control impulses. These apparatus are also relatively intricate and, due to the deflection principle as contrasted with a zero or balancing method, the control operation is of limited accuracy.

According to the feature of my invention exemplified by Fig. '1, a control system is provided which requires relatively small space, operates with high accuracy by permitting the application of a zero or balancing method, and can be operated with an extremely small adjusting period so as to be capable of following relatively fast-changing control magnitudes.

The control system according to Fig. 6 contains a measuring network E of the compensating or potentiometer type. The circuit contains a current source "I supplying a constant current. "I is an ammeter and 542 a current-regulating device such as in iron filament resistors. A rheostat is connected with the current source and has a slide contact 545 connected with a thermoelement I21 and the control coil 540 of a relay "5-, The thermoelement 52l represents the temperature feeler of the control system and is subjected, for instance, to the temperature in an electric furnace to be regulated. The relay coil when energized closes the contacts I" and I as illustrated.

The control mechanism-proper has a rotatable electrode member ill which is connected with the slide contact "I of the rheostat i so as to be controlled in synchronism therewith. The control mechanism further contains an insulating body "0 of cylindric shape carrying twocircular contact segments "I and 552. The contact member 5H, when rotating, moves sequentially over the contact members iii and 552. The se ments Ill and 552 are connected with the coils "I 'and 582 whose other ends are connected with each other and with the impulse-transmit- B. Fig. 6 shows the movable member III in a neutral position. At other moments of its movement, the member III is above one or the other of segments "I or III so that the dischargeof the control circuit occurs through member M I, one of the segments and the appertaining control coil "I or I82. That is, if the temperature measured by the feeler MI is abovea datum value, the balance condition of zero branch 590 is obtained at a moment when the member ill is above segment "I, so that the coil III is energized and interrupts the current supply to the furnace to be regulated. On the other hand, if the furnace temperature measured by the feeler "I is below the datum value, the member II I.

at the moment of balance is above segment "2 and causes the coil "2 to switch-in the current supply to the furnace.

According to another feature of the invention, the insulating carrier 550 with the contact segments I and 552 is adjustable angularly relative to the movable member 5| l. Such an aguting circuit C. The two coils I and B82 represent the main relay for controlling the electric furnace. Coil ill, for instance, when energized,

interrupts the furnace current, whilecoil 562,

when energized, supplies heating current to the furnace.

The slide contact 545 and the movable contact member I are rotated in synchronism with each other, During each cycle of its rotation, the slide contact I passes through a potentiometer position where the voltage produced by the temperature feeler Mi is compensated by a counter-voltage derived from the current source Hi. In this movement, the zero branch I", containing the relay coil 540, is free of current so that the coil lilll is deenergized. Consequently, in this moment the relay spring causes contact I01 to engage contact Hi9 and to energize the impulse-transmitting circuit. At the same time, the electrode or contact III of the control mechanism assumes a position relative to the stationary member 5" which corresponds to the compensating position of the slide contact lar adjustment has the effect of changing the location of the neutral position and thereby the datum value of the control operation. This renders it possible to select at will the temperature or other condition to be kept constant by the control system. The adjustment of'the mechanism, as regards the datum-value, may be effected manually or by automatic means. If automatic means are employed, the control operation is dependent not only on the variations of the above-mentioned primary control magnitude (1:) but responds also to the variation of a ond control magnitude (1/).

Fig. 7 represents an alternating currentsystem for recordingpurposes, in particular a system for the automatic recording over an extensive period of the blood or fever temperature of a patient. The current source of the system is designated by Gill and consists of mains to be connected to a customary utility network, for instance, by means of an ordinary plug-andsocket connection. The-recording'device contains a drum 823 to be covered with the recording chart and a movable member 6 rotating about the axis of the drum. This recording member is energized by means of an impulse-'- transmitting circuit C and contains an electrochemical writing device or a discharge electrode for producing a record by means of sparks. The movable member and the drum are automatical- 1y shifted relatively to each other in parallel to the drum axis, so that the movable member, aside from its rotation, travels lengthwise over the paper. The longitudinal (axial) movement 01' the drum, for the purpose here in view, is

preferably effected with constant speed.

The primary magnitude for controlling the recorder is supplied by means of a' thermometric device "I, preferably a resistance thermometer. This thermometer is, attached to the body of the patient, for instance with the aid of a bandage. .The resistance thermometer MI is connected with the measuring network B by means of a transformer 60!. Numerals 802, 625 and 028 designate resistances of substantially constant magnitude. The adjustable impedance member of the bridge network consists of a rheostat 603 having a rotary slide contact BM'connected with the zero branch 690 of the bridge arrangement. The network is connected with a step-down transformer 62!! which has its input circuit connected with the current source Gilli.-

Oil of the remain coupled with each other by 8- driving shalt I. which is actuated by means a motor "I. preferably of the synchronous type. The motor III! is also fed from the current source "0. The zero relay ill! or this system is connected with the zero branch II through an alternating current amplifier 822 whose energy supply is derived from the same current 'source "II. The relay "8 is of the dynamometric type and has its stationary field coil connected with the current source 600, The

impulse-transmitting circuit controlled by the j relay t" is similar to those of the other examples, except'that its current'source consists or a rectiiler Ill alsc'connected with the primary current source I06. However, it is also advantageous to connect thecontrol circuit with the amplifier I22. 1

The operation of the system shown in Fig. 7 is substantially similar to that or the preceding examples.

While for the purpose of recording temperatures, in particular blood temperatures, the axial movement of the drum "I is constant in time. a recorder of the type illustrated in Fig. 7v may also be designed as an 11-1! recorder so that the recorded magnitude is dependent upon the variations 01 two independent control magnitudes a: and 1!. similar 'to the operation or the a-u control apparatus previously described in connection with Fig. 6. For a:-y recording, the axial movement of drum III in. F18. 7 is effected by a -drive which operates in dependence upon the second control magnitude (1!) and varies its speed' accordingly. According to another'modiilcation of the invention, an :z-y recorder is so sacs-i a raw further possibilities, it is obvious that a plurality 0! indicating, recordin or control mechanisms may be connected with a single measuring network. Likewise, one and the same indicating, recording and control mechanism can be operated to respond alternately to diii'erout control magnitudes. For instance, a multiple recorder, having a recording chart and transport drum substantially as shown in Fig. 4, is obtainedby providing the apparatus with a contact device which connects the measuring system cyclically with difl'erent measuring arrangements. The recording apparatus then indicates cyclically the dlfierent magnitudes to be measured and records several curves. In order to facilitate distinguishing between these different magnitudes, the discharges in the control circuit and so on. A multiple recorder can also be prodesigned that the recording drum 623 is rotated with constant speed so as to perform one rotation for each recording operation of the movable member, while the latter is moved axially in response to the second control magnitude (y), for instance, by'rneans or a parallel mechanism.

Measuring systems, for signalling, indicating, recording or control purposes. according to the invention, are obtained with relatively simple means and afford a high accuracy and, if desired, a high speed oi operation unaiiected by vibrations, inconstancy of the current supply and the like disturbances. With respect to accuracy, it will be noted that the operation of the control relay is largely independent of the calibration or constancy of its return spring or other counter-force, dueto the fact that the control operation is effected by a zero method. The accuracy of operation is also independent of the speed and uniiormityoi the motionwith whlch'the adjustable impedance member and the movable member are actuated. When using an impliiier between the relay and the measuring network proper, as is exemplified by Fig. '1, the control operation is virtually independent of the constancy of the amplification iactor,-again because the circuit arrangement operates according to a zero method. In alternating current systems as shown in Figs. 4 and 8, the operation is also largely independent of variations in the voltage or current intensity of the primary current source. In the arrangement of Fig. 7, for instance, no particular requirements are made as to the constancy of the voltage supplied by the transformer As apparent from the examplesillustrated and described, the invention permits numerous modifications and may be carried out with additional or auxiliary circuits and devices. To mention vided in an arrangement having a drum recorder or the type shown in Fig. '7. In the latter case, the slide contact BM 01 the potentiometer and the movable recording member Eli are rotated over only a portion, for instance 90 or 120", of a circle. Consequently, the recording 01' each magnitude is limited to for instance A or /s 01 the drum periphery. For recording the variations of the second, third, etc., magnitude, the recording device is cyclically switched over so as to produce corresponding records on the second, third, etc., portions of the drum. Simultaneous f with this switching operation, the measurin syseffect a cyclic operation as described in the foregoing.

It is to be understood that when speaking in the foregoing of a periodic movement of the adiustable impedance and the indicating, recording or controlling member, I mean to include a continuous operation as well as an intermittent 'movement possessing, for instance, equal or anec' ual intervals of rest between the cycles of operation.

Iclaim:

l. In an electric system for effecting an indication in accordance with a. variable control ma nitude, a balanceable network comprising variable circuit means for supplying said control magnitude,. an adjustable impedance member to establish balance conditions, and a balance-respom sive control device, in combination with an indicating mechanism comprising a stationary scale and an indicator member movable relatively to saidscale and having illuminating means for producing flashes of light, drive means for periodically and simultaneously varying the adjustments of said impedance member and said indicator member in a given relation to each other and over a range-including the balance adjustment of said network, and a control circuit controlled by said balance-responsive member and connecting it with said illuminating means to produce during the periodic travel of said indicator member a light flash at the point of said scale which corresponds to the position of balance of said impedance member.

2. In an electric system for effecting an indication in accordance with a variable control magnitude, a balanceable network comprising-'variable circuit means for supplying said control magnitude, an adiustable impedance member to establish balance conditions, and a balance-responsive control device, in combination with an .indicating mechanism comprising a movable inof travel of said illuminating means and provided with luminous substance to indicate by afterglow the tendency of variation of the magnitude to be indicated. 4 I

3. A measuring network comprising periodically operating circuit means for producing impulses indicative of a magnitude to be determined, in combination with an indicating mechanism having a movable indicator member coupled with said circuit means so as to move in a given relation to the periodic operation of said means, said indicator member having illuminating means electrically connected with said circuit means for producingflashes of light in accordance with said impulses at a point of the path of travel of said indicator member which corresponds to said magnitude to be determined, and a, carrier extending along the path of travel of said illuminating means and provided with luminous substance to indicate by afterglow the tendency of variation of said'magnitude.

4. In an electric system for effecting a control in accordance with a variable magnitude, a balanceable circuit arrangement comprising variable circuit means for supplying said magnitude, an adjustable impedance member to establish balance conditions. and a balance-responsive control device, in combination with a control apparatus comprising two control members, one having a plurality of contacts insulated from one another and said other control member being movable relative to said first control member to cooperate with any one of said contacts depending upon the position of said control members relative to each other, drive means for periodically moving said control members relative to each other and for simultaneously varying the adjustment of said impedance member over a range of adjustment including the balance position, a plurality of circuit elements to be controlled, said circuit elements being connected with said plurality of contacts respectively, and a control circuit connecting said balance-responsive control device with said movable control member for transmitting a control impulse' to the contact located at the point of travel of said movable control member which corresponds to the posit on of balance of said adjustable impedance member thereby selecting for operation the circuit element connected with said latter contact.

'5. In an electric system for effecting a control in accordance with a variable magnitude, a balanceable circuit arrangement comprising variable circuit means for supplying said magnitude, an adjustable impedance member to establish balance conditions, and a balance-responsive control device, in v combination with a control apparatus comprising two control members, one having two contact segments and the other being movable over said contact segments to cooperate with either of them depending upon the relative position of said control members, drive means for periodically moving said control members relative to each other and for simultaneously varying the adjustment of said impedance member over a range of adjustment including the balance position, two windings for effecting the desired control proper with opposite control effects respectively, said windings being connected with said contact segments respectively, and a control circuit connecting said balance-responsive control device with said movable control memberfor causing it to pass a control impulse to the contact segment located at the point of travel of said movable control member which corresponds to the position of balance of said adjustable impedance member thereby selecting for operation thewinding connected with said latter contact segment.

6, In an 'electric system for effecting a control in accordance with a variable magnitude, a balanceable circuit arrangement comprising variable circuit means for supplying said magnitude, an adjustable impedance member to establish balance conditions, and a balance-responsive control device, in combination with a, control apparatus comprising two control members movable relative to each other, one having at least two contact segments and the other having a contact to cooperate withone of said segments depending upon the relative position of said control members, drive means for periodically moving one of said control members and simultaneously varying the adjustment of said impedance member over a range of adjustment including the balance position of said impedance member, said control member not subject to said periodic movement being hiftable relative to the driven control member to set the control members according to a desired control operation, at

least two control windings for effecting the desired control proper, said windings being connected with said contact segments respectively, and a control circuit connecting said balanceresponsive control device-with said driven control member and said windings for passing a control impulse through the contact segment located at the point of the periodic travel of said driven controlmember at which said impedance member passes through its position of balance thereby selecting for operation the winding connected with said latter segment.

7. In an electric system for effecting a control in accordance with a variable magnitude, a balanceable measuring network comprising variable circuit means for supplying said magnitude. a balance-responsive control device, a variable balancing impedance member having rotary adj.

iusting means for varying the impedance over a range including the balance adjustment, in combination with a control apparatus comprising two control members, the first being substantially stationary and having two insulated contact segments arranged in series along a circular path, the second control member being rotatable about said circular path to cooperate with either segment depending upon the position of said control members relative to each other, drive means for rotating said adjusting means and'said rotatable control member in synchronism with each other, said first control member having said two segments being shiftable anguiarly with respect to said driven control member to set said control apparatus according to a desired control operation, two control windings for effecting the desired control proper, said windings being connected with said contact segments respectively,

and a control circuit connecting said balance-responsive control device with said driven control member and said windings for passing a control impulse through the contact segment located at the point of the periodic travel of said driven control member at which said rotary adjusting means of said impedance member passes through its position of balance thereby selecting for oper-,

ation the winding connected with said latter segments.

8. A measuring system for actuating a mechanism for indicating, recording, or control purposes, which comprises a measuring network having circuit means of an impedance to be determined, an adjustable impedance member, a measuring device responsive to the impedance magnitudes of said circuit means and said impedance member, in combination with an impulse-transmitting circuit including a. condenser anda current source for charging said condenser, said mechanism to be actuated having two cooperative electrode members movable relative to each other and connected in said impulse-transmitting circuit, drive means for periodically varying the adjustment of said impedance member over an impedance range including the adjustment according to said given relation, one of said electrode members being coupled with said adjustable impedance member to move in synchronism with said periodic adjustment, contact means arranged for controlling said impulse-transmitting circuit and having a movable intermediate contact associated with said measuring device and two sta-" tionary outer contacts connected with said condenser and said current source respectively to discharge said condenser through said electrode members at the moment when the impedance of said impedance member and the relative position of said electrode members correspond to said given impedance relation and to charge said condenser in intermediate periods.

9. A measuring system for actuating a mechanism for indicating, recording, or control purposes, which comprises a balanceable measuring "network having a zero branch, a zero instrument in said branch, circuit means having an impedance to be determined and an adjustable imped- "ance member to balance the efl'ect of said impedance to be determined on said zero branch, in combination with an impulse-transmitting circuit including a condenser and a current source for charging said condenser, said mechanism to be actuated having two cooperative electrode members movable relative to each other and connected in said impulse-transmitting circuit, drive member over an impedance range including the balance adjustment, one of said electrode members being counted with said adjustable impedance member, to move in synchronism with said periodic adjustment, contact means arranged for controlling'said impulse-transmitting circuit and having a movable intermediate contactassociated with said zero instrument and two stationary outer contacts connected with said condenser and said current source respectively to discharge said condenser through said electrode members at the moment when said zero branch is balanced and to charge said condenser in intermediate periods.

10. An electric system for controlling a mechanism in accordance with a variable control magnitude, comprising in combination, circuit means for supplying said control magnitude, a relay con nected with said circuit means, means operatively associated with said relay for balancing the effect of said control magnitude on said relay, said balancing means having a movable member for varying the balancing actionof said means onsaid relay, said mechanism having a movable operating member connected with said movable balancingmember, drive means tor-periodically varying the positions of said two movable mem bers within a range including the balance adjustment of said movable member of said balancing means, a contact device forming part of said relay and comprising a movable contact arranged to respond to both said circuit means and said balancing means, and two stationary contacts arranged to limit the movement of said movable contact so as to effect a substantially instantaneous switching over of the latter from one to the other stationary contact when responding to said balance adjustment, a current source and a condenser connected with said movable contact and one of said stationary contacts to accumulate a current charge in said condenser when said movable contact engages said one stationary contact, and a control circuit connecting said other stationary contact and said condenser with said movable operating member of said mechanism so as to be rendered operative by said movable contact member when the latter member switches over to said other stationary contact, whereby in turn said movable operating member of said mechanism is rendered operative by said control means for-periodically adjusting said impedance magnitude so as to have said relay respond to the balance condition, said mechanism having a periodically movable operating member, means for periodically varying the adjustment of said 'variable'balancing means inv synchronism with the periodic movement of said mechanism memher, a control device having a movable element associated with said relay so as to be actuated thereby and two stationary elements arranged to limit the movement of said movable element for effecting a substantially instantaneous switching over of the latter from one to the other stationary element when said relay responds to said balance adjustment, current supply means for producing a current surge in order to energize said movable mechanism member, said current supply means being connected through said control device with said movable mechanism member so as to be controlled by said control device in response to the switching over of said movable element of said control device from one to the other of said stationary elements, whereby said movable mechanism member is rendered operative by a current surge from said current supply means at the point of the periodic travel of said mechanism member where said movable element of said contact device responds to the balance condition then adjusted by said variable balancing means.

12. An electric system for actuating a mechanism in accordance with a variable control magnitude, comprising a balanceable circuit arrangement comprising variable circuit means for supplying said control magnitude, an adjustable impedance member to establish balance conditions, and a control device having a balanceresponsive movable contact and two stationary contacts arranged to limit the movement of said movable contact so as to efiect a substantially instantaneous switching over of the latter from one to the other stationary contact when respondlng to said balance conditions, in combination with drive means for periodically varying the adjustment of said impedance member within a range including the balance adjustment, said mechanism having a movable actuating member mechanically connected with said impedance member to move synchronously with said latter member, and an impulse-transmitting circuit controlled by said control device and connected with said movable member of said mechanism, said circuit containing a condenser and a voltage source for charging said condenser and being connected with said movable contact and said stationary contacts so that said condenser is charged when said movable contact engages one of said stationary contacts and discharged through said movable mechanism member when said movable contact switches over to said other stationary contact, whereby said movable member is rendered electrically operative at the point of its periodic travel which corresponds to the balance position 01' said impedance member.

13. An indicating, recording or controlling measuring system, comprising a measuring network having variable circuit means for supplying a primary control magnitude, anadjustable impedance member, and a measuring device respon-. sive to said control magnitude oi said circuit means and to the impedance magnitude of said impedance member, in combination with contact a trol magnitude, said mechanism having two cooperative electrode members movable relative to each other and connected in said impulse-transii. In an alternating current system, the combination of a balanceable network having means for supplying an AC voltage, a branch containing variable circuit means for producing a control magnitude, a zero branch, an adjustable impedance member to balance said zero branch, and a dynamometric relay having a moving coil connected in said zero branch and a field coil connected with said AC supply means so as to be a movable contact and two stops for limiting the path of said movable contact to efi'ect a substantially instantaneous switching over of the latter when said relay responds to balance conditions in said zero branch, and an impulse-transmitting circuit controlled by said cont t device and connected with said movable mec anism member to energize the latter when said relay responds to balance conditions in said zero branch.

15. An electric system for recording a variable control magnitude, comprising in combination, a

relay, circuit means iorproviding said control magnitude, said circuit means being connected with said relay, variable means for counteracting the effect on said relay oisaid circuit means due to said control magnitude so as to have said relay respond to a given magnitude of a diflerential action, a recording device having two electrode members forming an interstitial gap between each other and being movable relative to each other, means for periodically moving one of said electrode members relative to said other member and for adjusting said variable circuit means in synchronism to said electrode movement, a contact device having a movable element associated with said relay so as to be actuated thereby, and two stationary elements arranged to limit the movement of said movable element i'oreflecting I a substantially instantaneous switching over of mitting circuit, said electrode members forming a gap between each other, drive means for periodicaly adjusting said impedance member over an impedance range including the adjustment according to said given relation, one of said electrode members being coupled with said adjustable impedance member to move in synchronism with saidperiodic adjustment, whereby said two members of said mechanism are energized by said impulse-transmitting circuit passing a current through said gap at a point of the relative travel of said electrode members which correspondsto said adjustmentoi said impedance member to said given relation.

the latter from one to the other stationary element when, said relay responds to said given I magnitude, a control circuit comprising a current source and connecting said contact device with said two electrode members to pass a current across said electrode gap at the point of said relative periodic movement of said electrode members where said movable element of said contact device switches over, whereby said recording device is caused to eflect a recording operation at said point.

16. Measuring apparatus comprising condition responsive means for providing a variable electric control magnitude, relay means, adjustable circuit means connected with said condition responsive means and said relay means so as to cause said relay means to change its condition when'said circuit means passes through an adjustment in-' dicative 01' said magnitude, means for varying the adjustment of said circuit means independently oi variations 01 said magnitude and through a predetermined range which includes said indicative adjustment, a mechanism to be controlled having two cooperative members movable relative to each other for performing an exhibiting operation, means for causing relative motion otsaid members simultaneously with and in proportion to the adjustment variation 01 said circuit means,

and an electric capacitive circuit controlled by 1 said relay means for controlling the exhibiting operation of said two members by capacitive current impulse occurring at a point of said relative motion corresponding to that 0! said indicative adjustment relative to said range.

17. The combination or a mechanism having two relatively movable members for performing adjustment of said adiusting means and simultaneously imparting cyclical relative motion to said mechanism members at correlated speeds independent of the variations oi said magnitude, and an impulse transmitting circuit disposed between said control means and said mechanism and having circuit means for producing current impulses terminating independently oi the action of said relay means so as to be substantially moinentary as compared with the period of said cyclical motion, said circuit being controlled by said control means for releasing an impulse vand thereby rendering said mechanism members temporarilyoperative at the moment when said control means change their condition in response to balance. I 1

18. An indicating, recording or controlling measuring system, comprising an electric network having condition-responsive means ior providing a variable electric magnitude in dependence upon variations of a condition under observation, an adjustable circuit member, and relay means arranged relative to said means and said member sofas to change its relay condition when said member passes through an adjustment indicative of said magnitude; a mechanism to be controlled in accordance with said magnitude having two cooperative electrode members movable relative to each other; drive means connected to said circuit member and to said mechanism for varying the adjustment of said circuit member through a predetermined cycle and simultaneously imparting relative motion to said electrode members in a given relation to the adjustment variation; and electric energy-storing means controlled by said relay means and connected to said mechanism for controlling its operation by passing a current impulse irom one to the other electrode member at the moment 01 said change in relay condition.

cannon maria. 

